Mantled Guereza

These strikingly patterned monkeys belong to a group that are mainly black and white. Mantled guerezas are found in a range of habitats, including the rainforests of the Congo, the forested hills of Nigeria’s Donga Valley and the wooded grasslands of East Africa. When in dense jungle, mantled guerezas spend their whole lives in the trees, but, in areas where trees are more widely dispersed, they often come down to the ground to feed and move between trees.

Mantled guerezas eat mainly leaves. Less than 20 per cent of their diet is made up of other items, mainly fruits. When possible, the monkeys eat fresh shoots, but will move on to tougher, older leaves when necessary.

These monkeys eat a specialist diet of leaves, which has led to their digestive system adapting to break down the cellulose so they can thrive on a high-fibre diet. In the upper part of the monkey’s stomach there are bacteria and protozoa that undertake this task, buffered by saliva produced in the salivary glands. This area is separated from the other part of the stomach, whose main function is simply to store the leaves.

The male guerezas are slightly larger than the females. The thumb on each hand is missing completely, and the remaining four fingers are used for swinging from 1 branch to branch.

Mantled guerezas live in small groups made up of one adult male, four or five adult females and their offspring. The adult females are close relatives. The young females stay with their troop as they mature, while the males are driven away by the resident male. When the dominant male is replaced by another, the new leader will kill the youngest infants. This brings their mothers into season again so the new male can breed with them.